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| United States Patent |
5,036,633
|
|
Kobori
, et al.
|
August 6, 1991
|
Variable damping and stiffness structure
Abstract
A variable damping and stiffness structure is disclosed, which includes a
variable damping device provided between posts, beams and braces of a
structure or braces serving as variable stiffness elements and
interconnecting a frame body and the variable stiffness element or the
variable stiffness elements themselves. Not only the unreasonance
property, but also the damping property of the structure are compositely
judged by a computer on the basis of information obtained from sensors
with respect to disturbances such as earthquake and wind to control the
connecting condition of the variable damping device, whereby both the
unresonance property and the damping property are controlled to reduce the
response amount of the structure. Otherwise, the variable damping device
is controlled by the judgement of only the damping property.
| Inventors:
|
Kobori; Takuji (Tokyo, JP);
Takahashi; Motoichi (Tokyo, JP);
Nasu; Tadashi (Tokyo, JP);
Niwa; Naoki (Tokyo, JP);
Kurata; Narito (Tokyo, JP);
Hirai; Junichi (Tokyo, JP);
Adachi; Yoshinori (Tokyo, JP);
Ishii; Koji (Tokyo, JP)
|
| Assignee:
|
Kajima Corporation (Tokyo, JP)
|
| Appl. No.:
|
475818 |
| Filed:
|
February 6, 1990 |
Foreign Application Priority Data
| Feb 07, 1989[JP] | 1-27901 |
| Feb 07, 1989[JP] | 1-27902 |
| Feb 07, 1989[JP] | 1-27903 |
| Feb 07, 1989[JP] | 1-27904 |
| Feb 23, 1989[JP] | 1-43565 |
| Mar 14, 1989[JP] | 1-61237 |
| Mar 23, 1989[JP] | 1-71182 |
| Current U.S. Class: |
52/1; 52/167.2 |
| Intern'l Class: |
E04A 009/00 |
| Field of Search: |
52/1,167 DF
|
References Cited
U.S. Patent Documents
| 4429496 | Feb., 1984 | Masri | 52/1.
|
| 4587773 | May., 1986 | Valencia | 52/167.
|
| 4799339 | Jan., 1989 | Kobori et al. | 52/1.
|
| 4841685 | Jun., 1989 | Masri et al. | 52/1.
|
| 4890430 | Jan., 1990 | Kobori et al.
| |
| 4901486 | Feb., 1990 | Kobori et al.
| |
| 4922667 | May., 1990 | Kobori et al.
| |
| 4959934 | Oct., 1990 | Yamada et al.
| |
Primary Examiner: Scherbel; David A.
Assistant Examiner: Smith; Creighton
Attorney, Agent or Firm: Tilberry; James H.
Claims
What is claimed is:
1. In a building structure, means to control the response of the structure
to external forces of seismic vibration and/or wind impacting against said
structure, comprising: variable stiffness means secured to and bracing
said structure; variable damping means having a variable coefficient of
damping interposed between said structure and said variable stiffness
means; and means to vary the coefficient of damping of said variable
damping means responsive to the magnitude of said external forces
impacting against said structure.
2. The means of claim 1, including computer means programmed to monitor
external forces impacting against said structure and to control said
variable damping means by selecting the coefficient of damping for said
variable damping means best suited to control the response of said
structure to said external forces and by actuating said variable damping
means.
3. The means of claim 2 wherein said coefficient of damping is selected to
render said structure non-resonant relative to the said monitored external
forces.
4. The means of claim 1, wherein said variable damping means comprises: a
double acting hydraulic cylinder; a shiftable piston in said hydraulic
cylinder dividing said cylinder into two concentrically opposed chambers;
a piston rod axially aligned and concentrically mounted in said piston to
extend through said opposed chambers; means to secure one end of said
piston rod to said structure; means to secure the other end of said rod to
said variable stiffness means; first means to pass a hydraulic fluid from
one chamber to the other chamber; valve means to control the flow of
hydraulic fluid in said first means; and means to control said valve
means, whereby the coefficient of damping of said variable damping means
is determined by the control of said valve means.
5. The means of claim 4, including second means to pass a hydraulic fluid
from one chamber to the other chamber; means to restrict the flow of
hydraulic fluid in said second means; said second means comprising a
bypass around said valve means in said first means.
6. The means of claim 1, wherein said variable damping means comprises: a
hydraulic cylinder; a shiftable piston in said hydraulic cylinder dividing
said cylinder into two opposed chambers; a piston rod axially aligned an
concentrically mounted in said piston to extend through said opposed
chambers; means to secure one end of said piston rod to said structure;
means to secure the other end of said rod to said variable stiffness
means; an oil pressure line with one end connected to one of said chambers
an connected to the inflow side of a variable damping control valve; an
oil pressure line connected at one end to the outflow side of said
variable damping control valve and at its other end to the other of said
chambers; means to pen and to close said variable damping control valve
wherein said piston is rendered immovable in said cylinder when said
variable damping control valve is closed and movable in said cylinder when
said variable damping control valve is open, whereby the coefficient of
damping of the variable damping means ia a first preselected value when
said variable damping control valve is closed and a second preselected
value when said variable damping control valve is open.
7. The means of claim 6, including means to actuate said means to open and
to close said variable damping control valve.
8. The means of claim 6, wherein said means to actuate said means to open
and to close said variable damping control valve is adapted to sense and
to respond to sensed external forces of seismic vibration and/or wind
impacting against said structure by controlling the opening and closing of
said means to open and to close said variable damping control valve.
9. The means of claim 6, wherein said means to open and to close said
variable damping control valve is adapted to pulse said variable damping
control valve with pulses of variable time intervals to thereby provide a
plurality of selectable coefficients of damping for said variable damping
means.
10. The means of claim 9, wherein said means to actuate said means to open
and to close said variable damping control valve comprises computer means
adapted to sense, to measure, and to evaluate external forces of seismic
vibration and/or wind impacting against aid structure and to transmit
signals to said means to open and to close said variable damping control
valve to provide a coefficient of damping commensurate with the
computer-sensed seismic and/or wind forces impacting against said
structure.
11. The means of claim 1, wherein said variable stiffness means comprises
cross braces secured between selected portions of said structure, and said
variable damping means is secured between said cross braces and said
structure.
12. The means of claim 1, wherein said structure comprises posts and beams,
said variable stiffness means comprises cross braces secured between said
posts and beams, and said variable damping means interconnects said cross
braces, posts and beams.
13. The means of claim 12, wherein said cross braces are segmented and said
variable damping means connects said segmented cross braces.
14. The means of claim 12, wherein said cross braces are of X-shaped
configuration, and said variable damping means forms the center of each of
said X-shaped cross braces.
15. The means of claim 12, including a quake-resisting wall secured to one
of said beams and said variable damping means secured between another of
said posts and said quakersisting wall.
16. The means of claim 12, wherein said cross braces comprise a pair of
V-shaped members with the apex ends of said members positioned adjacent
the midsection of a beam and the opposite ends of said members secured to
the opposite ends of a vertically spaced apart beam, and said variable
damping means secured between the apex ends of said members and said
midsection of said adjacent beam.
17. The means of claim 12, including a U-shaped member secured to the
underside of a beam and depending therefrom; a U-shaped member secured to
the topside of a beam spaced vertically below said first-mentioned beam
and projecting upwardly therefrom, and variable damping means
interconnecting said U-shaped members.
18. The means of claim 12, including a structure foundation, resilient
means interposed between said structure and said foundation, and variable
damping means connected between said structure and said foundation.
19. The means of claim 1, wherein said structure comprises vertical hollow
posts; variable stiffness means positioned within said posts; and variable
damping means interconnecting said variable stiffness means and said
vertical hollow posts.
20. The means of claim 19, wherein said variable stiffness means comprises
steel pipe spaced away from the interior walls of said vertical hollow
posts.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a variable damping and stiffness structure having
a variable damping device provided in a frame of the structure and
interconnecting a frame body and a variable stiffness element or variable
stiffness elements themselves provided in the frame, wherein an external
vibrational force or disturbance like an earthquake and wind is controlled
by a computer according to the vibration of the structure to thereby
reduce the response amount of the structure.
2. Description of the Prior Art
The present applicant has proposed various active seismic response control
systems and variable stiffness structures (for example, Japanese Patent
Laid-open No. Sho 62-268479 and U.S. Pat. No. 4,799,339), in which a
variable stiffness element in the form of a brace and a wall or the like
is incorporated into a post-beam frame of the structure, and the stiffness
of the variable stiffness element itself or the connecting condition of a
frame body and the variable stiffness element is varied to analyze the
property of an external vibrational force like an earthquake and wind by a
computer, so that the stiffness of the structure is varied to provide
unresonance with the external vibrational force to achieve the safety of
the structure.
Now, conventional active seismic response control systems observe mainly
the relationship between a predominant period of the seismic motion or the
like and a natural frequency (usually, the primary natural frequency is
often taken into consideration) of a structure, wherein a resonance
phenomenon is avoided by offsetting actively the natural frequency of the
structure relative to the predominant period to thereby improve the
reduction in the response amount.
However, since the seismic motion or the like is particularly
non-stationary vibrations, it is conceivable that the conventional active
seismic response control system does not necessarily carry out the optimal
control in the case where the predominant period is indistinct or a
plurality of predominant periods are present, for example.
SUMMARY OF THE INVENTION
While the conventional active seismic response control system mainly
observes the unresonance property, the present invention provides a
variable damping device between a frame body and a variable stiffness
element or in the variable stiffness element to control the damping
coefficient, whereby the vibration is controlled in consideration of the
damping property.
Namely, a variable damping and stiffness structure according to the present
invention is so constituted that a variable damping device capable of
varying the damping coefficient on two or multiple steps is interposed
between the frame body of the structure and the variable stiffness element
or in the frame body, and the damping corresponding to the vibration of
the frame body is obtained by a computer to vary actively the damping
coefficient of the variable damping device giving the damping, so that the
response of the structure to an external vibrational force is reduced.
While the variable damping device serves as a variable stiffness device for
varying the stiffness of the frame body as long as the variable damping
device controls only locked condition and the freed condition, for
example, the various damping coefficients are given by adjusting
delicately the connecting condition between the completely locked
condition and the completely freed condition to provide the natural period
of the frame body according to the damping coefficient and the vibrational
condition of the frame body.
As the variable damping device capable of varying two kinds of damping
coefficients C.sub.1, C.sub.2, a connecting device (hereinafter referred
to as a cylinder lock device), in which a cylinder is connected to the
variable stiffness element like a brace, and a piston rod of a double-rod
type reciprocating in the cylinder is connected to the frame body, is
conceivable. As shown in FIG. 3, the cylinder lock device has a switch
valve 15 provided in an oil path 14 interconnecting a pair of oil pressure
chambers 13 respectively located on both sides of the piston 12a, wherein
the variable damping device is controlled either to the free side first
condition or the locked side second condition by the opening or closing
operation of the switch valve 15. The oil path 14 is provided with an
orifice 16, whereby first damping coefficient C.sub.1 in the first
condition is realized by designing the size of the orifice. Referring to a
second damping coefficient C.sub.2, a second oil path 17 is provided as a
bypass for the switch valve 15, and an orifice 18 is provided also in the
second oil path 17, whereby the second damping coefficient C.sub.2 in the
second condition is realized by designing the size of the orifice 18. The
same may be said of a cylinder lock device of another type, in which a
cylinder 11 is connected to the frame body and a piston rod 12 is
connected to the variable stiffness element.
In the cylinder lock device 10 utilizing the oil pressure, a damping force
for the frame body is given as a resistance force proportional to the
power of the relative speed of the piston rod 12 to the cylinder 11. The
frame characteristics in this case are shown in FIGS. 4 and 5, in which
the solid line represents the frame characteristics in large amplitude and
the broken line represents the frame characteristics in small amplitude.
That is, the frame using the cylinder lock device shows different
characteristics depending on the magnitude of vibration (for example,
amplitude). Graphs shown in FIGS. 4 and 5 show the frame characteristics
in two kinds of vibrational levels (.+-.0.5 cm and .+-.3.0 cm in amplitude
between stories), and the natural period of the frame varies in a value of
the damping coefficient C (damping coefficient C.sub.01, of which the
damping factor h reaches the maximum at the large vibration level, and
damping coefficient C.sub.02, of which the damping factor h reaches the
maximum at the small vibration level) of the cylinder lock device, in
which the damping factor h of the frame reaches the maximum.
Assuming that the damping coefficient in the upper limit of the vibration
level to be controlled is equal with C.sub.01 of the above-mentioned
damping coefficient and the damping coefficient in the lower limit of the
vibration level to be controlled is equal with C.sub.02 of the
above-mentioned damping coefficient, and when the period in such the range
is always variable, as is apparent from FIG. 4, the first and second
damping coefficients C.sub.1, C.sub.2 will do if these coefficients
C.sub.1, C.sub.2 are defined respectively as follows;
C.sub.1 <C.sub.01, C.sub.2 >C.sub.02 ( 1)
Also, as is apparent from FIG. 5, these coefficients C.sub.1, C.sub.2 are
preferably defined as values not so much deviated from C.sub.01, C.sub.02
respectively.
Table-1 shows examples of the damping factor h and the primary natural
period of the frame relative to two kinds of defined damping coefficients
C.sub.1, C.sub.2.
TABLE-1
______________________________________
damping coefficient
magnitude of vibration
h (%) T (sec)
______________________________________
C.sub.1 small 10 1.0
large 25 1.0
C.sub.2 small 30 0.4
large 10 0.4
______________________________________
Provided that the selection of C.sub.1, C.sub.2 varies with the range of
the vibration level to be controlled and in the case where a range capable
of varying the period may be limited, C.sub.1, C.sub.2 are not necessarily
limited to the range represented in (1).
Further, the variable damping device for giving two kinds of damping
coefficients is not limited to the above-mentioned cylinder lock device,
but any other variable damping device will do so long as it is capable of
setting at least two kinds of damping coefficients to provide a damping
force proportional to the power of the relative speed.
The active seismic response control system in this case is constituted of
the variable damping device interposed between the frame body and the
variable stiffness element or in the variable stiffness element and
setting at least two kinds of damping coefficients C.sub.1, C.sub.2 as
noted above, frequency characteristic analyzing means, response amount
measuring means, damping coefficient selecting means and control command
generating means.
The external vibrational force input to a structure is sensed by a sensor
or the like installed in the structure or in the outside, and the
predominant period and other frequency characteristics are analyzed by the
frequency characteristic analyzing means in a computer program. The actual
response amount of the structure or that of the frame body is sensed by an
accelerometer, a speedometer, a displacement meter or like sensors serving
as the response amount measuring means. The unresonance property and the
damping property of the frame body are estimated and compositely examined
with reference to these frequency characteristics and the response amount
by the damping coefficient selecting means in a computer program, whereby
either of two kinds of the damping coefficients C.sub.1, C.sub.2 is
selected as the damping coefficient for reducing the response of the
structure. That is, case where the predominant period is indistinct and
the unresonance is impossible or the case where the damping control effect
is larger than the unresonance effect according to the distribution of a
period component such as the seismic motion is judged by the computer on
the basis of the obtained frequency characteristics and response amount to
select the damping coefficient. Further, the natural period of the frame
body or that of the structure results in either a long or short period
according to the vibration level by selecting the damping coefficient.
Thus, the natural period for the unresonance is selected by selecting the
damping coefficient according to the vibration level. The selected damping
coefficient is realized by giving the control command generated from the
control command generating means to the variable damping device.
As the cylinder lock device capable of varying the damping coefficient on
multiple stages or continuously, a cylinder lock device, in which a
cylinder is connected to the variable stiffness element such as a brace
and a piston rod of a double-rod type reciprocating in the cylinder is
connected to the frame body, for example is conceivable. As shown in FIG.
15, the cylinder lock device includes an orifice 35 capable of varying the
opening and provided in an oil path 34 interconnecting a pair of oil
pressure chambers 33 respectively located on both sides of a piston 32a,
whereby the damping coefficients ranging from the small damping
coefficient at the freed side having the large opening to the large
damping coefficient at the locked side having the small opening are
adjusted on multiple stages or continuously by adjusting the opening of
the orifice. As the orifice 35, use is particularly made of a high speed
switch valve or the like controlled in response to a pulse signal through
a pulse generator or the like. As shown in FIG. 16, the various openings
and the various damping coefficients accompanying the change in the
opening are realized by varying a valve opening time. The time, during
which the valves are closed in the order from above to below in FIG. 16 is
elongated and the dimensional relationship among the damping coefficients
C.sub.1, C.sub.2, C.sub.3 under the respective conditions is as follows:
C.sub.1 <C.sub.2 <C.sub.3
Otherwise, the opening may be adjusted by any mechanical constitution.
The same may be said of a cylinder lock device of another type, in which a
cylinder 31 is connected to the frame body and a piston rod 32 is
connected to the variable stiffness element.
In the cylinder lock device 30 utilizing the oil pressure, the damping
force for the frame body is given as a resistance force (P=cv.sup.r)
proportional to the power of the relative speed of the piston rod 32 to
the cylinder 31, and the frame body shows the characteristics varying with
the magnitude of vibration (for example, amplitude).
The frame characteristics in this case are as shown in FIGS. 17 and 18.
That is, the frame using the cylinder lock device shows the characteristics
varying with the magnitude of vibration (for example, amplitude). Graphs
shown in FIGS. 17 and 18 show the frame characteristics in five kinds of
vibration levels ranging from the large vibration of about several cms of
story amplitude to the small vibration of about several mms of story
amplitude. In the vicinity of values C.sub.1, C.sub.2, C.sub.3, C.sub.4
and C.sub.5 of the damping coefficient in which the damping factor h of
the frame in each vibration level reaches the maximum, the natural period
(primary natural period) of the frame is varied from the long natural
period T.sub.1 to the short natural period T.sub.2. Also, as is apparent
from these graphs, the larger the vibration is, the smaller the damping
coefficient of the variable damping device producing the maximum damping
effect is.
Referring to the control observing only the damping property, the response
of the structure is reduced by adjusting the damping coefficient of the
variable damping device according to the vibration level of the frame such
that the damping effect of the frame is maximized by utilizing the frame
characteristics.
The active seismic response control system in this case is constituted of
the variable damping device interposed between the frame body and the
variable stiffness element or in the variable stiffness element and
capable of varying the damping coefficient as noted above, response amount
measuring means, damping coefficient selecting means and control command
generating means.
When the external vibrational force is input to the structure, the response
amount of the structure or that of the frame body is sensed by an
accelerometer, a speedometer, a displacement meter or like sensors serving
as the response amount measuring means. A large damping property is given
to the structure according to the vibration level by the damping
coefficient selecting means in the computer program to select a value of
the optional damping coefficient C for reducing the response of the
structure. The selected value of the damping coefficient C is realized by
giving the control command to the variable damping device from the control
command generating means, that is, by adjusting the opening of the switch
valve of the variable damping device.
Also, in the control in consideration of both damping property and
unresonance property, assuming that the damping coefficient for maximizing
the damping factor h of the frame is C.sub.i in a certain vibration level,
as is apparent from FIG. 17, the damping coefficient C.sub.il =C.sub.i
-a(a>0) which is somewhat smaller than the damping coefficient C.sub.i
results in the longer natural period T.sub.1 of the frame and the damping
coefficient C.sub.i2 =C.sub.i -b(b>0) which is somewhat larger than the
damping coefficient C.sub.i results in the shorter natural period T.sub.2
of the frame. With reference to FIG. 18 showing the relationship between
the damping coefficient C of the variable damping device and the damping
factor h of the frame, either of the natural period T.sub.1, or T.sub.2,
which is advantageous for the frame in the facet of the unresonance
property, is realized, and the response of the structure is reduced in
both facets of unresonance and damping effect by selecting (defining a or
b as small as possible in an extent of satisfying the requirements of the
natural period) such damping coefficient to make the damping effect of the
frame large as much as possible. When the effect on unresonance property
cannot be so much expected, for example, in the case where the predominant
period of the seismic motion is indistinct, however, the large damping
effect can be expected by selecting the damping coefficient C.sub.i
maximizing the damping factor h of the frame for the damping coefficient
of the variable damping device.
Further, the variable damping device providing the damping coefficients on
multiple stages or continuously is not limited to cylinder lock device,
but any other variable damping device will do as long as it gives the
damping force proportional to the power of the relative speed.
The active seismic response control system in this case is constituted of
the variable damping device interposed between the frame body and the
variable stiffness element or in the variable stiffness element and
capable of varying the damping coefficient as noted above, frequency
characteristic analyzing means, response amount measuring means,
unresonance property estimating means, damping property estimating means,
damping coefficient selecting means and control command generating means.
The external vibrational force input to the structure is sensed by sensors
installed in the structure or in the outside thereof, and the predominant
period and other frequency characteristics are analyzed by the frequency
characteristic analyzing means in the computer program. On the other hand,
the actual response amount of the structure or that of the frame body is
sensed by an accelerometer, a speedometer, a displacement meter or like
sensors serving as the response amount measuring means, and the
unresonance property and the damping property of the frame body are
estimated by the unresonance property estimating means and the damping
property estimating means in the computer program with respect to the
frequency characteristic and the response amount, so that the damping
coefficient for reducing effectively the response of the structure is
selected by judging compositely the unresonance property and the damping
property of the frame body. For example, the unresonance property is
estimated with respect to two kinds of natural periods T.sub.1, T.sub.2
given to the frame body by the variable damping device, and when the
effect on the unresonance property due to either natural period is judged
to be larger, the damping coefficient for realizing the natural period
selected in an extent of giving the damping property as large as possible
in the response amount, i.e., the vibration level is selected. If the
predominant period is indistinct and the unresonance cannot be provided,
for example, only the damping property is contemplated to select the
damping coefficient giving the maximum damping to the structure. The
selected damping coefficient is realized by giving the control command
generated from the control command generating means to the variable
damping device.
OBJECT OF THE INVENTION
A primary object of the present invention is to reduce the response amount
of a structure by varying the damping coefficient of a connecting device
interposed between a frame body and a variable stiffness element to
compositely estimate and control the resonance property and the damping
property of the structure, whereby the safety of the structure is ensured,
while a comfortable residential space is realized.
Another object of the present invention is to reduce the response amount of
a structure by previously grasping the frame characteristics such as the
relationship between the vibration level and the damping coefficient in
order to control the disturbance such as a seismic motion in consideration
of the damping property of the structure, and then controlling the damping
property corresponding to the response amount of the structure. Namely,
the damping coefficient of the variable damping device is varied to vary
the connecting condition of the variable stiffness element and the
variable damping device, and the optimal damping property corresponding to
the characteristics of the structure is provided to reduce the response
amount of the structure, whereby the safety of the structure is ensured,
while the comfortable residential space is realized.
A further object of the present invention is to perform the more rational
control by judging the resonance property and the damping property at the
same time to compositely estimate and control the resonance property and
the damping property of the structure for the input disturbance and the
response of the structure.
A still further object of the present invention is to more rationally
control the response of a structure by performing the control in
consideration of not only the unresonance property but also the damping
property of the structure for the disturbance such as a seismic motion,
even when the effect on reduction of the vibration due to the unresonance
in little.
A yet further object of the present invention is to provide a variable
damping device suitably used for controlling the vibration of a structure
by estimating the resonance property and the damping property.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view showing a variable damping and stiffness
structure, to which a first active seismic response control system is
applied according to the present invention;
FIG. 2 is a chart of control in accordance with the first active seismic
response control system;
FIG. 3 is a conceptional view showing a cylinder lock device as an
embodiment of a variable damping device used in the first active seismic
response control system;
FIGS. 4 and 5 are graphs for explaining the frame characteristics in a
structure, to which the first active seismic response control system is
applied, respectively;
FIGS. 6 through 12 are graphs showing the relationship between the seismic
motion characteristics of the control in accordance with the first active
seismic response control system and the response amount in each of two
kinds of damping coefficients, respectively;
FIG. 13 is a schematic view showing a variable damping and stiffness
structure, to which a second active seismic response control system is
applied according to the invention;
FIG. 14 is a flow chart of control in accordance with the second seismic
response control system;
FIG. 15 is a conceptional view showing a cylinder lock device as an
embodiment of a variable damping device used in the second and third
active seismic response control systems;
FIG. 16 is a view for explaining the relationship between the damping
coefficient of the variable damping device and pulse signals in the case
where the opening of an orifice using a high speed switch valve is
adjusted in response to the pulse signal to be controlled by a valve
opening time;
FIGS. 17 and 18 are graphs for explaining the frame characteristics of a
structure, to which the second and third active seismic response control
systems are applied, respectively;
FIG. 19 is a schematic view showing a variable damping and stiffness
structure, to which the third active seismic response control system
according to the present invention is applied;
FIG. 20 is a flow chart of control in accordance with the third active
seismic response control system;
FIG. 21 is an oil pressure circuit diagram showing an embodiment of the
cylinder lock device to be used in the first active seismic response
control system;
FIG. 22 is an oil pressure circuit diagram showing an embodiment of the
cylinder lock device to be used in the second and third active seismic
response control systems;
FIGS. 23 through 30 are schematic views showing the positions, in which the
variable damping device is applied to the frame of the variable damping
and stiffness structure according to the present invention, respectively;
FIG. 31 is a vertical sectional view showing an embodiment of the variable
damping and stiffness structure sub to bending deformation control;
FIG. 32 is a sectional view taken along the line I--I in FIG. 31;
FIG. 33 is a sectional view taken along the line II--II in FIG. 31;
FIG. 34 is an elevation showing the outline of a building in the case of
the variable damping and stiffness structure;
FIG. 35 is a plan view showing the building of FIG. 34;
FIG. 36 is a conceptional view showing the cylinder lock device serving as
the variable damping device;
FIG. 37 is a schematic view showing a building under the normal condition;
FIG. 38 is a constitutional view showing the cylinder lock device under the
normal condition;
FIG. 39 is a schematic view showing a building under the condition that the
building has low damping to earthquake and wind or is free from damping;
FIG. 40 is a constitutional view showing the cylinder lock device under the
condition as shown in FIG. 39;
FIG. 41 is a schematic view showing a building under the condition that the
building has high damping to earthquake and wind or is locked; and
FIG. 42 is a constitutional view showing the cylinder lock device under the
condition as shown in FIG. 41.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
First will be described an embodiment of a control system used for a
variable damping and stiffness structure according to the present
invention.
Active seismic response control system 1
In this system, a variable damping device having two kinds of specified
damping coefficients C.sub.1, C.sub.2 set is interposed between a frame
body and a variable stiffness element or in the variable stiffness
element, and the unresonance property and damping property are compositely
judged to control the vibration of a structure by varying the connecting
condition of the variable damping device.
FIG. 1 shows the outline of the constitution of the active seismic response
control system according to the present invention. A variable damping
device 1 (for example, the cylinder lock device as noted above) is
interposed between a frame body 2 composed of posts 3 and beams 4 and an
inverted V-shaped brace 5 provided as a variable stiffness element and
incorporated in the frame body 2 of each story. The input seismic motion
and the response (amplitude, speed, acceleration or the like) of a
structure thereto are respectively sensed by an input sensor 6 and a
response sensor 7, and the damping coefficient of the variable damping
device 1 corresponding to the seismic motion characteristics (predominant
period) and the response condition is obtained by a computer 8 to output a
control command. FIG. 2 shows the flow of the process in the above
control.
More particularly, the control is carried out as follows;
(1) A vibration level for the control is set. For example, .+-.0.5 to
.+-.3.0 cm of story deformation amount, and 1 to 25 kine (cm/sec) of speed
or the like.
(2) The frame characteristics in the upper and lower limits of the set
vibration level is grasped. For example, the variation of period and
damping factor of the frame body due to the damping coefficient of the
variable damping device or the like.
(3) The period shall be able to surely vary in the set vibration level, and
further the damping coefficient C.sub.1, C.sub.2 of the variable damping
device capable of additionally producing the effect on damping to the
frame as large as possible shall be selected so that either C.sub.1 or
C.sub.2 is selected according to the control command.
(4) The damping property is estimated (feed-back control) according to the
response of the structure, and the unresonance property is estimated
(feed-forward control) according to the seismic motion characteristics
(predominant period) so that the composite control becomes possible.
(5) In a small vibration (wind and small earthquake), the damping
coefficient C.sub.2 for producing the largest effect on damping in the
small vibration level is normally selected.
Table-2 shows a summary of control manners in the seismic motion
characteristics corresponding to FIGS. 6 through 12 as the embodiments of
control. Further, in FIGS. 6 through 12, the ordinate represents response
values, the abscissa represents periods, the solid line represents the
response spectrum of a seismic motion, the dot-dash line represents the
response value when the damping coefficient C.sub.1 is selected, the
broken line represents the response value when the damping coefficient
C.sub.2 is selected, the black circle represents the response value in the
selected damping coefficient and the white circle represents the response
value in the other damping coefficient not selected.
TABLE-2
__________________________________________________________________________
Vibration
Seismic motion character-
Selected damping
Damping factor of frame, primary
Number
level
istics and others
coefficient
natural period and comments
__________________________________________________________________________
1 small
FIG. 6 C.sub.2 h = 30%, T = 0.4 sec
This case has the largest effect in
damping. Unresonance is impossible
2 small
FIG. 7 C.sub.1 h = 10%, T = 1.0 sec
This case is effective in unresonance
more than damping
3 small
FIG. 8 C.sub.2 h = 30%, T = 0.4 sec
This case is effective in damping
more than unresonance
4 small
FIG. 9 C.sub.2 h = 30%, T = 0.4 sec
This case has the effect both in
damping and unresonance
5 large
FIG. 10 C.sub.1 h = 25%, T = 1.0 sec
This case has the same effect
as that in No. 1
6 large
FIG. 11 C.sub.2 h = 10%, T = 0.4 sec
This case has the same effect
as that in No. 2
7 large
FIG. 12 C.sub.1 h = 25%, T = 1.0 sec
This case has the same effect as that
in No. 4, while the damping coefficient
is C.sub.1.
__________________________________________________________________________
Active seismic response control system 2
FIG. 13 shows the outline of a variable damping and stiffness structure in
the system 2. A variable damping device 21 (for example, the cylinder lock
device as noted above) is interposed between a frame body 22 composed of
posts 23 and beams 24 and an inverted V-shaped brace 25 provided as a
variable stiffness element and incorporated in the frame body 22 of each
story. The response (amplitude, speed, acceleration or the like) of a
structure in an earthquake is sensed by a response sensor 26 provided in
the structure, and the optimal damping coefficient of the variable damping
device 21 corresponding to the response condition, i.e., vibration level
is obtained by a computer 28 to generate a control command. FIG. 14 shows
the flow of the process in the above control.
In a cylinder lock device 30 making use of oil pressure shown in FIG. 15 as
noted above, a damping force relative to the frame body is given as a
resistance force proportional to the power of the relative speed of a
piston rod 32 to a cylinder 31. The frame characteristics in this case are
as shown in FIG. 18. The graph in FIG. 18 shows the frame characteristics
in five kinds of vibration levels ranging from the large vibration having
about several cms of story amplitude to the small vibration having about
several mms of story amplitude, in which reference numeral C represents
the damping coefficient of the variable damping device and h represents
the damping factor of the frame. As is apparent from this graph, the
larger the vibration is, the smaller the damping coefficient C of the
variable damping device producing the maximum effect on damping is.
In this embodiment, the damping coefficient of the variable damping device
is adjusted according to the vibration level of the frame by making use of
the frame characteristics such that the damping effect of the frame
reaches the maximum, so that the response of the structure is reduced.
More particularly, the control is carried out as follows:
(1) First, the magnitude of vibration (amplitude, speed, acceleration or
the like) of the structure, the damping coefficient C of the variable
damping device and the damping effect h of the frame are grasped in
relation to the control.
This corresponds to that the frame characteristics shown in FIG. 5 are
grasped with respect to a plurality of vibration levels, for example and
the damping coefficients C.sub.1, . . . , C.sub.n giving the maximum
damping effect h of the corresponding structure or the frame are obtained
with respect to the levels ranging from the large vibration level L.sub.1
to the small vibration level L.sub.n.
(2) The damping coefficient C minimizing the vibration of the structure is
incessantly calculated by the computer on the basis of the above
characteristics to control the variable damping device. This control
results in the feed-back control since the variable damping device is
controlled while the vibrational condition of the structure is monitored.
The control in the system 2 is thus fed back according to the response
amount of the structure to be relatively simply carried out by previously
grasping the relationship between the vibration level and the damping
coefficient.
Active seismic response control system 3
FIG. 19 shows the outline of a variable damping and stiffness structure in
the system 3. The input seismic motion and the response of the structure
(amplitude, speed, acceleration) are sensed respectively by an input
sensor 56 and a response sensor 57, and the damping coefficient of a
variable damping device 51 according to the seismic motion characteristics
(predominant period) and the response condition is obtained by a computer
58 to generate a control command. FIG. 20 shows the flow of the process in
the above control.
The variable damping device 51 is as same as the variable damping device in
the system 2. However, as is apparent from FIGS. 17 and 18, in respective
vibration levels, the natural period (primary natural period) of the frame
is also varied from the long natural period T.sub.1 to the short natural
period T.sub.2 in the vicinity of values C.sub.1, C.sub.2, C.sub.3,
C.sub.4 and C.sub.5 of the damping coefficients maximizing the damping
factor h of the frame.
Assuming that the damping coefficient maximizing the damping factor h of
the frame in a certain vibration level is C.sub.1 as above mentioned, the
natural period of the frame results in the longer natural period T.sub.1
in the damping coefficient C.sub.il =C.sub.i -a(a>0) which is somewhat
smaller than the damping coefficient C.sub.i as shown in FIG. 17, while in
the damping coefficient C.sub.i2 =C.sub.i -(b>0) which is somewhat larger
than the damping coefficient C.sub.i, the natural period of the frame
results in the shorter period T.sub.2. This is collated with FIG. 18
showing the relationship between the damping coefficient C of the variable
damping device and the damping factor h of the frame. The natural period
which is advantageous for the frame having either natural period T.sub.1
or T.sub.2 in the facet of unresonance property is realized, and the
response of the structure is reduced in both facets of unresonance and
damping effect by selecting such the damping coefficient to make the
damping effect of the frame as large as possible (by taking the
aforementioned a or b as small as possible within a range of satisfying
the requirements of the natural period). However, when the predominant
period of the seismic motion is indistinct and the effect on the
unresonance properly is not so much expected, for example, a large damping
effect is expected by selecting the damping coefficient C.sub.1 maximizing
the damping factor h of the frame as the damping coefficient of the
variable damping device.
Hereinafter will be described this effect in relation to the flow chart
shown in FIG. 20.
The external vibrational force input to the structure is detected by
sensors provided in the structure or in the outside to analyze the
predominant period and other frequency characteristics. On the other hand,
the actual response amount of the structure of that of the frame body is
detected by sensors such as an accelerometer, a speedometer and a
displacement meter, and the unresonance property and the damping property
of the frame body are estimated by the computer with reference to the
frequency characteristics and the response amount to compositely judge the
frequency characteristics and the response amount, so that the damping
coefficient for reducing effectively the response of the structure is
selected. For example, the unresonance property in two kinds of natural
periods T.sub.1, T.sub.2 given to the frame body by the variable damping
device is estimated. When the effect of the unresonance property due to
either natural period is judged to be large, the damping coefficient for
realizing the selected natural period is selected within the range of
giving the damping property as large as possible in the response amount,
i.e., vibration level at the time of the judgement. When the predominant
period is indistinct, and the unresonance is not possible to be attained,
for example, the damping coefficient giving the maximum damping to the
structure is selected in consideration of only the damping property. The
selected damping coefficient is realized by giving the control command
from the control command generating means to the variable damping device.
More particularly, the control is carried out as follows;
(1) First, the magnitude (amplitude, speed, acceleration or the like) of
the vibration of the structure, the damping coefficient C of the variable
damping device, the damping effect h of the frame and the period T are
grasped in relation to the control.
This, for example, corresponds to that the frame characteristics shown in
FIGS. 17 and 18 are grasped in a plurality of vibration levels, and the
damping coefficients C.sub.1, . . . C.sub.n giving the maximum damping
factor h for the corresponding structure or the frame are obtained ranging
from the large vibration level L.sub.1 to the small vibration level
L.sub.n.
2) The damping coefficient C of the variable damping device is incessantly
calculated by the computer such that the vibration of the structure is
minimized on the basis of the characteristics to control the variable
damping device.
(3) The damping coefficient C of the variable damping device is selected on
the basis of the following three points:
i. The unresonance of the structure is realized against the seismic motion
(feed-forward control). The damping coefficient C capable of realizing
such the natural period to make the response of the structure smaller is
selected on the basis of the frequency analysis of the seismic motion.
ii. The damping coefficient C giving the damping effect of the frame body
as large as possible is selected according to the vibration condition of
the structure (feed-back control), provided it is selected within the
extent of realizing the natural period set in (i).
iii. When the effect due to the unresonance is little, the damping
coefficient C maximizing the damping effect of the frame body is selected.
Table-3 summarizes the control in accordance with the system 3
corresponding to the frame characteristics shown in FIGS. 17 and 18.
TABLE-3
______________________________________
magnitude of seismic motion
optimal damp-
vibration kind of line
characteristics
ing coefficient
______________________________________
large (1) solid line T = 0.4 C.sub.1-1
T = 1.0 C.sub.1-2
small (4) two dots- T = 0.4 C.sub.4-1
chain line T = 1.0 C.sub.4-2
medium (2)
dotted line
same C.sub.2
______________________________________
On Table-3, numerals in parenthesis in the column of the magnitude of
vibration represent the vibration levels shown in FIGS. 17 and 18 in the
order from the smaller level to the larger level, and the kind of lines
indicates that in the drawings. Also, the seismic motion characteristics
shown the natural period of smaller response spectrum out of two kinds of
natural periods given by the variable damping device.
That is, on Table-3, when the vibration level is large (1) and the period
component of 0.4 seconds is much for the seismic motion characteristics,
the damping coefficient C.sub.1-1 shown in FIGS. 17 and 18 is selected.
When the period component of 1.0 second is much, the damping coefficient
C.sub.1-2 is selected. Similarly, when the vibration level is small (4)
and the period component of 0.4 second is much for the seismic motion
characteristics, the damping coefficient C.sub.4-1 is selected, and when
the period component of 1.0 second is much, the damping coefficient
C.sub.4-2 is selected. The lowermost row on Table-3 shows the case where
there is little difference in the response spectrum between two kinds of
natural periods, i.e., 0.4 secs and 1.0 sec of the frame. In this case,
the damping coefficient C.sub.2 giving the maximum damping property to the
frame is selected.
Next will be described an embodiment of the variable damping device used in
each of the active seismic response control systems 1 to 3.
FIG. 21 shows an embodiment of an oil pressure circuit of a variable
damping device 61 used in the active seismic response control system 1. As
shown in the drawing, a device body includes left and right oil pressure
chambers 65 located at the left and right of a piston 63 of a double-rod
type reciprocating in a cylinder 62. Pressurized oil in the left and right
oil pressure chambers 65 is confined or adapted to flow by a change-over
valve 70 used for large flow, so that the piston 63 is fixed or moved to
the left and right.
One of the cylinder 62 and the rod 64 is connected to one of the frame body
of the structure and the variable stiffness element of one of the variable
stiffness elements themselves, and the other is connected to the other of
the frame body and the variable stiffness element or the other of the
variable stiffness elements themselves.
The left and right oil pressure chambers 65 are provided respectively with
left and right outflow blocking check valves 66 for blocking the outflow
of pressurized oil from the respective oil pressure chambers 65 and left
and right inflow blocking check valves 67 for blocking the inflow of
pressurized oil into the respective oil pressure chambers 65. An inflow
path 68 for interconnecting the left and right outflow blocking check
valves 66 themselves and an outflow path 69 for interconnecting the left
and right inflow blocking check valves 67 themselves are provided along
the body of the cylinder 62.
A change-over valve 70 for the large flow is provided in the
interconnecting position of the inflow path 68 and the outflow path 69 and
has an inlet port 72 and an outlet port 73 provided on one end side of a
valve body and a back pressure port 74 provided on the other end side, for
example. A shut-off valve 71 for blocking the outflow of pressurized oil
toward the back pressure port 74 is provided in the flow path on the side
of the back pressure port 74, a great capacity of pressurized oil is
adapted to flow at high speed and to instantly shut off.
Further, according to the present invention, a bypass flow path is provided
for passing the pressurized oil under the throttled condition even if the
large flow change-over valve 70 is closed, and the damping coefficient is
varied between the first damping coefficient C.sub.1 under the opened
condition and the second damping coefficient C.sub.2 (>C.sub.1) under the
closed condition by opening and closing the large flow change-over valve
70.
More particularly, as conceptionally shown in FIG. 3, the inflow path 68 or
the outflow path 69 is provided with a first orifice 75. By designing the
opening of the orifice 75, the predetermined first damping coefficient
C.sub.1 under the opening condition of the large flow change-over valve 70
is given, and by providing the orifice in the bypass flow path for the
large flow change-over valve 70 or by designing the bypass path itself as
an orifice 76, the predetermined second damping coefficient C.sub.2 under
the closed condition of the large flow change-over valve 70 is given, for
example.
This variable damping device 61 is of a double-rod cylinder type, in which
the length of a flow path is shortened by providing two paths, i.e., the
inflow path 68 and the outflow path 69, the check valves 66, 67 and the
large flow change-over valve to along the cylinder 62, and a large flow of
pressurized oil is adapted to flow at high speed and to instantly shut off
by expanding the flow path area to reduce the path resistance. Also, the
flow path is instantly opened and closed by the use of the back pressure
system large flow change-over valve 70, so that the response speed is
extremely increased in cooperation with the constitution thereof as noted
above.
Next will be described the operating condition of the variable damping
device 61.
(1) Large flow change-over valve is open
When the shut-off valve 71 is opened, the piston 63 is moved to the left in
FIG. 21, so that the pressurized oil of the left oil pressure chamber 65
flows through the inflow blocking check valve 67 and the outflow path 69
to push up the large flow change-over valve 70.
Since the left outflow blocking check valve 66 and the right inflow
blocking check valve 67 are closed due to the pressurized oil, the
pressurized oil flows from the large flow change-over valve 70 through the
inflow path 68 and the right outflow blocking check valve 66. Thus, the
pressurized oil flows from the left oil pressure chamber 65 to the right
oil pressure chamber 65 to move the piston 63 to the left due to the
external force.
Then, the orifice 75 in the outflow path 69 functions to give a resistance
for against the flow of pressurized oil. Thus, the predetermined small
damping coefficient C.sub.1 approximate to that under the freed condition
will be given to the device 61 by designing the opening of the orifice 75.
Even in the case where the piston 63 is moved to the right, the pressurized
oil works symmetrically, so that the piston 63 is moved to the left due to
the external force.
(2) Large flow change-over valve is closed
When the leftward external force is exerted to the piston 63 under the
closed condition of the shut-off valve 71, oil pressure to the large flow
change-over valve 70 is increased to push up the change-over valve 70.
However, since the oil pressure in the back pressure port 74 is received
by the shut-off valve 71, the large flow change-over valve 70 is also
fixed under the closed condition to block the movement of the piston 63,
provided that the pressurized oil flows through the orifice 76, as it
receives the resistance, since the orifice 76 is formed in the bypass for
the change-over valve 70 as mentioned above.
Thus, when the large flow change-over valve 70 is closed, the damping
coefficient C.sub.2 which is large than that under the opened condition
and approximate to that under the fixed condition will be given.
The same may be said of the case where the rightward external force is
exerted to the piston 63.
When the variable damping device 61 making use of the oil pressure is
provided between the frame body and the variable stiffness element, the
damping force for the frame body is given as a resistance (P=cv.sup.r)
approximately proportional to the power of the relative speed of the
piston 63 to the cylinder 62 and, as mentioned above, the frame body shows
the different characteristics depending on the magnitude (for example,
amplitude) of vibration.
Further, in the above embodiment, each of the check valves 66, 67 is so
constituted that a right-like valve body is urged by the action of a
spring to flow the pressurized oil only in one direction, for example.
Also, the shut-off valve 71 is changed over in two positions, i.e.,
opening and closing positions by the use of a solenoid 77. Further, as
shown in the drawing, an accumulator 78 communicating to the inflow path
68 is mounted on the cylinder 62. The accumulator serves as an oil
reservoir for pressurizing the pressurized oil in the cylinder 62 with a
pressure resulting from adding .alpha. to the atmospheric pressure (i.e.,
the atmospheric pressure+.alpha.) to supply the oil in leakage, prevent
the oil from mixing with bubbles, and compensate for a volume change due
to the change of temperature and the compression of the oil in the
locking.
FIG. 22 shows an embodiment of an oil pressure circuit of a variable
damping device 81 used in each of the active seismic response control
systems 2 and 3. As shown in the drawing, the device body includes left
and right oil pressure chambers 86 located on the left and right of a
piston 83 of a double-rod type reciprocating in a cylinder 82. Pressurized
oil in the left and right oil pressure chambers 86 is confined or caused
to flow by a valve, sot hat the piston 83 is fixed or moved to the left
and right.
One of the cylinder 82 and the rod 84 is connected to one of the frame body
of the structure and the variable stiffness element or one of the variable
stiffness elements themselves, and the other is connected to the other of
the frame body and the variable stiffness element or the other of the
variable stiffness elements themselves.
The left and right oil pressure chambers 86 are provided respectively with
left and right outflow blocking check valves 88 for blocking the outflow
of pressurized oil from the respective oil pressure chambers 86 and left
and right inflow blocking check valves 89 for blocking the inflow of
pressurized oil into the respective oil pressure chambers 86. An inflow
path 90 for interconnecting the left and right outflow blocking check
valves 88 themselves and an outflow path 91 for interconnecting the left
and right inflow blocking check valves 89 themselves are provided along
the cylinder body 82.
A flow regulating valve 92 is provided in the connecting position of the
inflow path 90 and the outflow path 91 to be opened and closed in response
to the pulse signal from a pulse generator connected to a computer, so
that the damping coefficient C of the variable damping device 81 can be
adjusted by varying the opening of the flow regulating valve 92.
This variable damping device 81 can be conceptionally considered to be a
simplified form as shown in FIG. 15. For example, the variable damping
device serves as a variable stiffness device for varying the stiffness of
the frame body if only the locked condition, of which the flow regulating
valve 92 is completely closed, and the freed condition, of which the flow
regulating valve 92 is completely closed, and the freed condition, of
which the flow regulating valve 92 is completely opened, are controlled.
On the other hand, by adjusting the opening of the flow regulating valve
92 to delicated adjust the connection condition between the completely
locked condition and the completely freed condition, various damping
coefficients C are given to provide the natural period and the damping
factor h of the frame body at the time of adjustment according to the
damping coefficient C and the vibrational condition of the frame body.
The opening of the flow regulating valve 92 is considered in relation to
the time by adjusting the interval of pulse signals sent from the pulse
generator. That is, as shown in FIG. 16, the various openings and various
damping coefficients C accompanying the change in opening are realized by
varying the time, during which the flow regulating valve 92 is opened.
More particularly, as shown in the drawing, the flow regulating valve 92
has an inlet port 95 and an outlet port 96 provided on one end side of a
valve body, and is composed of a change-over valve 92a having a back
pressure port 97 provided on the other end side of the valve body and a
shut-off valve 92b provided in a bypass flow path 98 interconnecting the
inlet port 95 of the change-over valve 92a and the back pressure port 97
and capable of blocking the outflow of pressurized oil to the back
pressure port 97. The shut-off valve 92b is opened and closed in response
to the pulse signals sent from the pulse generator on the reception of the
command from the computer, and the change-over valve 92a is operated with
the opening and closing of the shut-off valve.
Also, an accumulator 99 is preferably provided in the inflow path 90 or the
outflow path 91 in order to compensate for the volume change due to the
compression of working fluid and the change of temperature.
This variable damping device is of a double-rod cylinder type, in which the
length of a flow path is shortened by providing two paths, i.e., the
inflow and outflow paths, the check valve and the flow regulating valve
along the cylinder, and a large flow of pressurized oil is adapted to flow
at high speed and to instantly shut off by expanding the flow path area to
reduce the path resistance. Also, the flow path is instantly opened and
closed by the use of the back pressure type flow regulating valve, so that
the response speed is extremely increased in cooperation with the
constitution thereof as noted above.
Next will be described the operating condition of the variable damping
device 81 according to this embodiment.
(1) Flow regulating valve is opened
When the shut-off valve 92b is opened, the piston 82 is moved to the left
in the drawing, so that pressurized oil int eh left oil pressure chamber
86 flows through the inflow blocking check valve 89 and the outflow path
91 to push up the change-over valve 92a.
Since the left outflow blocking check valve 88 and the right inflow
blocking check valve 89 are closed due to the pressurized oil, the
pressurized oil flows from the change-over valve 92a through the inflow
path 90 and the right outflow blocking check valve 88. Thus, the
pressurized oil flows form the left oil pressure chamber 86 to the right
oil pressure chamber 86 to move the piston 82 to the left due to the
external force.
Even in the case where the piston 82 is moved to the right, the pressurized
oil works symmetrically, so that the piston is moved to the left due to
the external force.
(2) Flow regulating valve is closed
When the shut-off valve 92b is closed and the leftward external force is
exerted to the piston 82, the oil pressure o the change-over valve 92a is
increased to push up the piston 82. However, since the bypass flow path 18
is shut off by the shut-off valve 92b to receive the oil pressure in the
back pressure port 97, the change-over valve 92a is also fixed under the
closed condition to block the movement of the piston 82. The same may be
said of case where the rightward external force is exerted to the piston
82.
When the variable damping deice 81 making use of the oil pressure as noted
above is provided between the frame body and the variable stiffness
element, the damping force for the frame body is given as a resistance
force (P=cv.sup.r) proportional to the power of the relative speed of the
piston 82 to the cylinder 62, and the frame body shows the different
characteristics depending on the magnitude (for example, amplitude) of
vibration.
FIGS. 23 through 30 show the positions, in which two kinds of variable
damping devices as noted above are applied to the frame of the structure.
In an embodiment shown in FIG. 23, a variable damping device 101 is
interposed between a post-beam frame serving as a frame body 102 and an
inverted V-shaped brace 105 serving as the variable stiffness element.
In an embodiment shown in FIG. 24, the variable damping device 101 is
interposed between a post-beam frame serving as the frame body 102 and
frames 111 themselves erected on or suspended from upper and lower beams
104 to constitute a moment resisting frame as the variable stiffness
element.
In an embodiment shown in FIG. 25, the variable damping device 101 is
interposed between a post-beam frame serving as the frame body 102 and a
RC quake resisting wall 112 serving as the variable stiffness element.
In an embodiment shown in FIG. 26, the variable damping device 101 is
provided on the foundation of a base isolation structure in combination
with base isolation rubber such as laminated rubber. In the case, the
variable damping device 101 serves as a damper in the base isolation
structure, and the variable stiffness element may be considered to be the
foundation of the structure.
In an embodiment shown in FIG. 27, a X-shaped brace 114 provided in the
post-beam frame serving as the frame body 102 is provided in the post-beam
frame serving as the variable stiffness element, and the variable damping
device 101 is interposed laterally (lateral type) in the center of the
X-shaped brace.
FIG. 28 shows an embodiment similar to that shown in FIG. 27, in which the
variable damping device is applied to the X-shaped brace 115. While the
embodiment shown in FIG. 27 is of a lateral type, in which the variable
damping device 101 is provided laterally, this embodiment shown in FIG. 28
is of a vertical type, in which the variable damping device is provided
vertically.
An embodiment shown in FIG. 29 is similar to that shown in FIG. 25, in
which the variable damping device 101 is interposed between a post-beam
frame serving as the frame body 102 and a RC quake resisting wall 116
serving as the variable stiffness element. The embodiment shown in FIG. 29
has a feature in that the variable damping device 101 is provided above
and opening 117 of a doorway or the like.
In an embodiment shown in FIG. 30, the variable damping device 101 is
interposed in the center of a X-shaped brace 118 in a large frame, and an
intermediate large beam 119 is separated from the brace 118.
FIGS. 31 through 42 show embodiments of the present invention applied to
structure like high-rise buildings having large bending deformation, and
any of the control systems 1 through 3 is applied to these embodiments as
the control system.
The vibration of the high-rise building due to an earthquake and wind
includes the shearing deformation of the frame due to the bending
deformation and the shearing deformation of the post and beam and the
bending deformation of the whole frame due to the axial deformation of the
post. Usually, the vibration of the building takes place as the total of
aforementioned two deformations, and the higher the height of a slender
building is relative to the width thereof, the larger the bending
deformation of the whole frame is.
On the other hand, the conventional variable stiffness structure often cope
with the above deformation by controlling the stiffness of the frame on
every story, so that the complicated control is necessary to cope with the
bending deformation, and the rational control is not always obtained.
In this embodiment, a rod-like control member extending over at least a
plurality of stories in the height direction of the building is provided
along the post of the building of a plurality of stories. The upper and
lower portions of the control member are respectively connected to
portions of the building, preferably the uppermost and lowermost portions.
The variable damping device capable of varying the connecting condition is
provided on the way or the end of the control member and adapted to
control the stiffness or the damping force of the building in the form of
control of the bending deformation against the vibrational disturbance
like an earthquake and wind.
Referring to FIGS. 31 through 33, an inside steel pipe 121 serving as the
control member is provided inside an outside steel pipe 122 constituting
an outer post 122a of a high-rise building. The inside steel pipe 121 has
the uppermost and lowermost portions respectively rigidly connected to a
connecting plate 126 and a diaphragm 15. The axial force of the outside
steel pipe 122 in the uppermost portion is transmitted to the inside steel
pipe 121 and the axial force of the inside steel pipe 121 in the lowermost
portion is transmitted to the underground post and the foundation.
Also, as shown in FIG. 33, the inside steel pipe 121 on the reference story
is separated from the diaphragm 124 in the post-beam connection through a
fine gap to permit the axially relative movement of the inside steel pipe
121 according to the condition of a cylinder lock device 130 provided in
the lower portion of the inside steel pipe 121.
FIGS. 34 and 35 show the outline of a building, respectively. In this
embodiment, the above double-steel pipe structure is applied to only the
outer post 122a on the outer periphery of the building having a large
effect, and the normal structure is applied to the inside post 122b. Also,
the cylinder lock device 130 is provided on the first story portion of the
outside post 122a.
FIG. 36 is a conceptional view showing the cylinder lock device 130
corresponding to that shown in FIG. 15. A double-rod type piston 132a is
inserted into a cylinder 131 and a switch valve 135 is provided in an oil
path 134 for interconnecting left and right oil pressure chambers 133
located on the left and right of the piston 132a. The damping and
resistance forces can be varied actively by controlling the opening of the
switch valve 135 on multiple stages. Also, when the opening of the switch
valve 135 is selected between the fully opened condition and the fully
closed condition of the opening, two conditions, i.e., the freed and
locked conditions can be realized. Further, a damping force in this case
is given as a resistance force proportional to the relative speed of the
piston 132a to the cylinder 131 or the power of this relative speed.
This cylinder lock device 130 is provided on the way of the inside steel
pipe 121 to be connected thereto such that the motion of the post 122a due
to its expansion and contraction results int he relative displacement of
the piston 132a to the cylinder 131 of the cylinder lock device 130.
When the cylinder lock device 130 is controlled under two conditions, i.e.,
freed and locked conditions as above mentioned, the cylinder lock device
can be controlled inc consideration of the unresonance property by
allowing the post to be expanded and contracted or restraining the post
from its expansion and contraction similarly to the case of the
conventional active seismic response control system and variable stiffness
structure. Also, the cylinder lock device can be controlled inc
consideration of the damping property or both the unresonance property and
the damping property according to the frame characteristics of the
building by controlling the switch valve 135 on multiple stages or
providing an orifice having the proper opening to adjust the damping
coefficient of the cylinder lock device 130.
The following table (Table-4) and FIGS. 37 through 42 summarize the
relationship between the deformed condition of the building and the
condition of the cylinder lock device 130 or the like, respectively.
TABLE-4
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load earthquake or wind
device normal time
low damping coefficient or free
high damping coefficient or
__________________________________________________________________________
lock
deformed condition
FIG. 37
FIG. 39 FIG. 41
of building
condition of device
FIG. 38
FIG. 40 FIG. 42
-- Since the switch valve is
Since the switch valve is
almost opened, the piston moves
almost closed, the piston moves
without much resistance.
while it receives much resistance.
.delta. -- large small
.DELTA.l -- large small
T -- long short
N 0 small large
remarks -- The inside steel pipe is not
The inside steel pipe is sufficiently
so much effective, the stiffness
effective, the stiffness is hard and
is soft and the natural period
the natural period becomes shorter.
becomes longer.
__________________________________________________________________________
.delta.: horizontal deformation (uppermost portion)
.DELTA.l: expansion and contraction of outer post
T: primary natural period of building
N: axial force of inside steel pipe
As shown in FIGS. 37 and 38, in the normal time when the vibrational
disturbance hardly occurs, the building is not substantially deformed and
the switch valve 135 of the cylinder lock device 130 does not need to be
controlled.
FIGS. 39 and 40 show the case where the switch valve 135 is fully opened or
almost opened. In this case, the inside steel pipe 121 is hardly effective
and the natural period becomes longer. The control under such the
condition as noted above is carried out for the seismic motion or the like
having the short predominant period in the seismic response control system
according to the judgement only depending on the unresonance property.
Also, when the control is carried out in consideration of the damping
property, a large damping force is obtained for a great earthquake having
the large vibration level by increasing the opening of the switch valve
135 (the valve 135 is almost opened) of the cylinder lock device 130.
FIGS. 41 and 42 show the case where the switch valve 135 is fully closed or
almost closed. In this case, the inside steel pipe 121 is sufficiently
effective and the natural period becomes shorter. The control in such the
condition as noted above is carried out for the seismic motion or strong
wind having the long predominant period in the seismic response control
system according to the judgment only depending on the unresonance
property. Also, when the control is carried out in consideration of the
damping property, a large damping force is obtained for medium and small
earthquake having the small vibration level by reducing the opening of the
switch valve 135 (the valve 135 is almost closed) of the cylinder lock
device 130.
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